I received the same email.
I used about half my sample bottle in a DWC plant a few months ago. I had no issues with the stuff, seemed to raise my PPM a little bit, tho i doubt i have a record of it handy... maybe in one of my old threads its in a chart.
I was going to use the other half in a side by side. but iv been rockn with my soiless at the moment, but i do have a couple dwcs goin again in the next couple of months, maybe that will be the time to do it.
I have been using Floralicious + in my DWC so it would be pretty hard to judge whiteness of the roots.